Acknowledging an action throttles further executions of that action until its
ack.state is reset to awaits_successful_execution. This happens when the
condition of the watch is not met (the condition evaluates to false).

You can acknowledge multiple actions by assigning the actions parameter a
comma-separated list of action ids:

POST _xpack/watcher/watch/my_watch/_ack/action1,action2

To acknowledge all of the actions of a watch, simply omit the actions
parameter:

POST _xpack/watcher/watch/my_watch/_ack

The response looks like a get watch response, but only contains the status: